Flow Visualization by Conditional Sampling of a Single X-Wire Probe in a Very Long Run Experiment

Flow visualization techniques using tracer markers such as die, smoke, hydrogen bubbles, etc., have been widely used in experimental investigations of large scale structures of a variety of flow fields. They have played an important role in understanding the physics of the coherent structures formation and evolution in the transitional as well as the turbulent regions of the flow fields. However, they lack to provide detailed quantitative information about the flow. Here, a new approach is taken in obtaining quantitative flow field snapshots from a region of a two-dimensional free shear flow mixing layer. A single cross-wire probe is used to make measurements of the flow in a time frame phase locked with the coherent flow structures which facilitates reconstructed flow snapshots from the hot-wire measurements in a very long run experiment. A new detailed calibration updating scheme is developed to resolve the problem of calibration validity encountering very long time hot-wire measurements. This is a key factor in facilitating reconstructed flow snapshots that satisfy the continuity equation with a very high accuracy.